a(n) is the number of permutations of length n that avoid the pattern 231 and the mesh pattern (12, 174) or the same sequence for the mesh pattern (12, 238).
A289447
a(n) is the number of permutations of length n that avoid the pattern 231 and the mesh pattern (12, 174) or the same sequence for the mesh pattern (12, 238).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =4a(4) =10a(5) =31a(6) =97a(7) =316a(8) =1054a(9) =3586a(10) =12394a(11) =43396a(12) =153604a(13) =548731a(14) =1975873a(15) =7163908a(16) =26131510a(17) =95829358a(18) =353100382a(19) =1306618696a(20) =4853643916a(21) =18092491990a(22) =67655720026a(23) =253727789944a(24) =954081100780
External references
- oeis: A289447